1. Field of the Invention
The present invention relates to a complementary signal generator for outputting a positive-phase signal and an antiphase signal complementary to each other.
This application is counterpart of Japanese patent applications, Serial Number 278802/2003, filed Jul. 24, 2003, the subject matter of which is incorporated herein by reference.
2. Description of the Related Art
As this type of complementary signal generator, there is known one which outputs complementary signals formed by input and output signals of inverters to switch, by complementary signals to be outputted, a plurality of switches connected so as to switch the other end of a capacitor whose one end is connected to an inversion input terminal thereof between a non-inversion input terminal and an output terminal with a view toward canceling an offset of a voltage follower, for example (e.g., refer to Patent Document 1).
As the complementary signal generator as well, there is known one having an input terminal for inputting an input signal and first and second output terminals for respectively outputting a positive-phase signal and a negative-phase or antiphase signal, and having a configuration wherein a first logic circuit for performing a timing adjustment to the input signal is connected between the input terminal and the first output terminal, and a second logic circuit for performing an output timing adjustment to the antiphase signal is connected even between the input terminal and the second output terminal (refer to Patent Document 2, for example).
(Patent Document 1)
    Japanese Laid Open Patent Application No. Hei 2001-188615 (FIG. 4 in third page)(Patent Document 2)    Japanese Laid Open Patent Application No. Hei 6-152346 (FIG. 1 in third to fourth pages)
In the circuit using the inverters as in the Patent Document 1 referred to above, no signal is propagated as long as the input signal to each inverter does not exceed a threshold voltage thereof. Therefore, an inversion timing is shifted between the input and output signals of the inverters, which are used as the complementary signals. Further, the Patent Document 2 was also similar to the Patent Document 1 in that complementary signals shifted in inversion timing were outputted.
A problem arises in that when, for example, the offset cancel circuit is driven by the complementary signals shifted in inversion timing as mentioned above, the timing provided to charge or discharge the capacitor becomes inaccurate, so that the cancellation of the offset is not performed accurately.
An object of the present invention is to provide a complementary signal generator which outputs complementary signals aligned in at least one inversion timing of inversion timings provided two in one period, in order to solve the above-described problems.